H. J. Lowe — Devonshire Geology. 273 



area. Now supposing that the Eocene land stretched to the utmost 

 boundary westward, and that its slope was eastward from almost it& 

 western limits, probability must be further strained to assume such 

 a large river within so narrow a strip of land. 



What is mox'e remarkable, however, is that, although so large and 

 swift a stream, it brought down no foreign material whatever^ 

 for these gravels contain only chalk and greensand debris with some 

 other fragments of rocks that are to be found in their immediate 

 neighbourhood. This negative evidence must surely be of fatal 

 import, since even though the chalk area stretched further westward 

 than Devonshire, still it would hardly be considered possible that the 

 whole coarse of the river was during its term of existence only over 

 and through the same Chalk formation. 



These gravels are assigned to the Bagshot age of the Eocene era, 

 which means a lapse of time subsequent to the close of the Cretaceous 

 period, during which the new Tertiary land subsided eastward, 

 allowing the formation of the lower Eocene members, viz., the 

 Thanet beds, the Reading beds, and the London Clay, totalling some 

 500 feet of new deposits, before the gravels in question are supposed 

 to be formed from the long upraised chalk land. Now although 

 this geological hiatus within this area must be inferred in order that 

 the Eocene era might half spend itself before the appearance of the 

 river to form these gravels, yet strangely and unfortunately no 

 distinctive forms of Eocene life are found among its fossils ; indeed, 

 only such paleeontological evidence is met with in them as to declare 

 them to be simply chalk and greensand debris. May not this be 

 taken as an indication of earlier formation than that assigned ? — 

 a supposition in keeping with the observation that the material 

 of the deposits and conditions of formation were unsuitable for 

 gathering and preserving contemporary biological evidence. 



Now these difficulties which seem to naturally arise with the 

 assumption that the gravels are river-borne do not present themselves 

 when the older theory referred to by Mr. Reid (ante, p. 271) by the 

 words "litoral Cretaceous rocks" are considered. De la Beche thus 

 accounts for them : — "From the unrolled condition of a large proportion 

 of the flints in the neighbourhood of Lyme Regis, Sidmouth, Chard, 

 and Blackdowns, we are led to suppose that the chalk in which they 

 were embedded may have been quietly removed from among them, 

 and that these flints may have been let down nearly in places above 

 which they occurred in the chalk." ^ Quoting again from Mr. W. H, 

 Hudleston's address: — " Speaking of the geology of the neighbour- 

 hood of Dawlish, Mr. Ussher says there can be little doubt that the 

 Cretaceous highlands of Devon, such as the Haldons, are portions of 

 a great plain of marine denudation, and he speaks of a time when 

 that Cretaceous tableland abutted on the flanks of Dartmoor." - 



The facts, then, pertaining to the gravels of the area in question 

 can be accounted for, without involving inferential difficulties, by 



1 Op. cit., p. 255. 



* Trans. Devon. Assoc, 1889, p. 32. 



DECADE V. VOL. II. NO. VI. 18 



